Vehicle powerplant systems, including engines and their related fluid delivery system, have employed various diagnostic techniques to determine if component degradation is present. Certain diagnostic routines target injector functionality, specifically, as one example.
U.S. Pat. No. 7,980,120 B2 to Cinpinski et al., discloses a system that monitors rail pressure while a pump is shut-down and an injector is actuated to determine if the injector is degraded. The inventors have recognized several drawbacks with the diagnostic method set forth U.S. Pat. No. 7,980,120. For example, the diagnostic routine requires the pump to be shut-down thereby impacting the system's ability to continue operation at a desired pressure during the diagnostic routine.
Other systems utilize a combination of multiple delivery systems, such as both direct and port injection to the engine. These combined systems allow for greater injection adaptability, thereby enabling the engine to achieve decreased emissions and increased efficiency. In these systems isolation valves may be used to separate the port injection side of the system from the direct injection side. The isolation valve may act to dampen pressure pulsations that are generated by the direct injection pump, to reduce the pump's impact on the system. However, the isolation valve may degrade (e.g., become stuck open), thereby impacting the valve's ability to dampen pressure pulses in the system. Consequently, the port injector's ability to provide repeatable injections may be diminished and noise, vibration, and harshness (NVH) in the fluid delivery system may also be increased.
To overcome at least some of the aforementioned problems a method for operating a fluid delivery system is provided. The method includes sampling a pressure in a port injection section of the fluid delivery system, determining if an isolation valve positioned upstream of a first pump is degraded based on the pressure, where the isolation valve separates the port injection section from a direct injection section, and when it is determined that the isolation valve is degraded, indicating degradation of the isolation valve. In this way, a degraded isolation valve can be accurately diagnosed and indicated. Consequently, mitigating actions and/or repairs may be carried out to reduce the unwanted impacts of the degraded isolation valve. The mitigating actions may be taken during servicing of the engine, in one example. In other examples, the mitigating actions may implemented on-board the vehicle responsive to the indication of a degraded isolation valve. For instance, the fluid delivery system may transition into a port injection mode or a direct injection mode in response to a determination that the isolation valve is degraded.
It should be understood that the summary above is provided to introduce in simplified form a selection of concepts that are further described in the detailed description. It is not meant to identify key or essential features of the claimed subject matter, the scope of which is defined uniquely by the claims that follow the detailed description. Furthermore, the claimed subject matter is not limited to implementations that solve any disadvantages noted above or in any part of this disclosure.